The present invention relates to devices or structures for containing and handling material, including medical, diagnostic, pharmaceutical or cosmetic substances, and to methods for making such devices or structures.
In some embodiments, the present invention relates to a multi-layered plastic body for handling medical, diagnostic, pharmaceutical and cosmetic products. Primarily, the plastic body serves to store or conduct fluid products including gelatinous products or is provided for storing or conducting the same.
An array of plastics have the property that they form fractures when under mechanical stresses and when acted on by a fluid, i.e., a liquid, gas or gel, wherein the fractures can cause components formed from such plastics to fail. The mechanical stresses may be caused by an external force acting on a component and/or by internal stresses. As a rule, the fluid interacts purely physically with the plastic, fractures only forming if the plastic material in question is under tensile stress. The tensile stress can be caused by an external force or in particular by internal stresses, e.g., frozen-in expansions and transverse stresses. This behaviour is also known by the term stress fractures or as environmental stress cracking (ESC). The fluid acting on the plastic can be a product to be conducted or stored or a fluid from the external environment of the plastic body, for example alcohol, or a component of a fluid, for example atmospheric oxygen, or other environmental substance, for example sebaceous matter. In the former case, the plastic body is acted on from within, and in the latter case from without. In most applications or uses, the plastic body is acted on from within and from without in conjunction, wherein, in many applications, one of these actions is more critical for the formation of fractures, wherein the focus can be on preventing or at least impeding the same.
Containers, filters, conduit systems and other simple catheters in medical, pharmaceutical or diagnostic applications, though also in cosmetic applications, generally have to fulfil a number of different functions simultaneously. In particular, the material of which they consist must not have a tendency towards stress fractures which can be triggered by the stored or conducted products, or by environmental influences.